an introduction to the flood estimation handbook · 2 school of civil engineering and geosciences...
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![Page 1: An Introduction to the Flood Estimation Handbook · 2 School of Civil Engineering and Geosciences Requirements Time resolution Ł hours and minutes, not days Space resolution Ł Specific](https://reader031.vdocuments.us/reader031/viewer/2022022607/5b84c7e87f8b9aea498cffbb/html5/thumbnails/1.jpg)
School ofSchool ofCivil Engineering and GeosciencesCivil Engineering and Geosciences
Chris KilsbyChris KilsbyUniversity of NewcastleUniversity of Newcastle
Building Knowledge for a Changing ClimateBuilding Knowledge for a Changing Climate
Precipitation Scenarios
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
RequirementsRequirements
Time resolution� hours and minutes, not days
Space resolution� Specific to sites, not grid boxes
Properties� realistic amounts, intensities, extremes� seasonality� long time series � multiple events
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
ApproachApproach
Stochastic rainfall modelling� To achieve downscaling in time and space� To generate long series� To interface with CRU weather generator
Building on:� UKCIP02 scenarios and UKMO climatology� Consistency with the FEH extremes� 15 years development at Newcastle� The StormPac approach
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Rainfall modellingRainfall modelling
The GNSRP model� A stochastic rainfall modelling system� Generalised Neyman-Scott Rectangular Pulses� Can generate arbitrarily long series (e.g. 1000
years) of rainfall� Applied to historic, control and future climates� Reproduces key statistical properties of rainfall
series, e.g. mean, variance, dry hours, 2, 5, 10, 25year annual maxima);
� Time resolution of 1-hour or 1-day
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Rainfall modellingRainfall modelling
� Storm origins arrive in aPoisson process
� Each origin generates arandom number of rain cells
� A rectangular pulse isassociated with each rain cell
� The total rainfall at any timeis the sum of all active raincells
time
time
time
inte
nsity
time
tota
l int
ensi
ty
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Work Plan - 1Work Plan - 1
Historic case� Set up the GNSRP model for the whole UK
using the MetOffice/UKCIP 5-kmclimatology.
� Parameterise to match observed 1961-1990 rainfall:
� means, variance, proportion dry hours etc� return period rainfalls - 2,5,10 or 25 year events
using observed data and FEH DDF model
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Work Plan - 1Work Plan - 1
18 sitesin 9 regions> 10 years
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Dyce
Hemsby
Warcop
Leeming
Tulloch
Ringway
Manston
Cranwell
Leuchars
Heathrow
Turnhouse
Stornoway
Yeovilton
St Mawgan
Aldergrove
AbbotsinchEskdalemuir
Hillsborough
ourly rainfall recordsRegions
CEEESNEENINSNWESEESSSWE
$ Hourly gaug
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Work Plan - 1Work Plan - 1
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RegionsCEEESNEENINSNWESEESSSWE
# Daily gaug
Daily rainfall records204 sitesin 9 regions40 years
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Work Plan - 2Work Plan - 2
Future climate� Parameterise for the whole UK for future
climates by using control and future outputfrom HAdRM3
Sub-hourly resolution� Use cascade model to disaggregate data
from 60 � 30 � 15 minute level� Reliability to be established below 15 minute
� depends on validation data
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10
School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Work Plan - 3Work Plan - 3
� Interface from GNSRP model to CRU dailyWG.
� Extend model to allow for changingproportion of convective/frontal rainfall infuture climate
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11
School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Summary - DeliverablesSummary - Deliverables
Rainfall model� for use by partners;� within the project;� to generate rainfall series;� at any site in UK� arbitrary length� time resolution of 1-day, 1-hour and below� control and future climates� reproduces observed extreme rainfall (up to
at least 25 year return period)
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
DataData
Observed daily rainfalldata 1961-2000
Daily rainfall data fromRCMs 1961-1990 and2070-2100
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
ChangesChanges
East Scotland 10-day
22 5 10 25 50 100 200 500
0
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-2 -1 0 1 2 3 4 5 6 7
Reduced Variate
Rain
fall
(mm
)
61-7071-8081-9091-00
50-yr event
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
What does this mean for the UK?What does this mean for the UK?
Change in recurrence interval for a 50-year event in 1961-1990 during 1991-2000
ES 1 in 8 yearSS 1 in 11 yearNS 1 in 25 yearNWE 1 in 25 yearNEE 1 in 25 year
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School of Civil Engineering and GeosciencesSchool of Civil Engineering and Geosciences
Future projectionsFuture projections
� (a) and (b) showHadRM2 projected %change in magnitude of10-yr and 50-yr 1 dayevent during 2080-2100
� (c) and (d) show samefor HadRM3 (UKCIP02)scenarios
(d)(c)
(b)(a)
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